1. Field of the Invention
The present invention relates to a wireless relay communication system. More particularly, the present invention relates to an apparatus and a method for Automatic Retransmission reQuest (ARQ) of a Media Access Control (MAC) layer in a wireless relay communication system.
2. Description of the Related Art
In a data exchange between a transmitter and a receiver in a wireless communication system, an error may occur according to a channel condition of radio resources. Error control and recovery techniques include Automatic Retransmission reQuest (ARQ) and a Forward Error Check (FEC). When ARQ is implemented, the receiver requests retransmission of corrupted data from the transmitter. When FEC is implemented, the receiver corrects the corrupted data.
When the wireless communication system adopts ARQ, the receiver determines if there is an error by decoding a received packet. When the received packet has no error, the receiver sends an ACKnowledge (ACK) message to the transmitter. When the received packet has an error, the receiver sends a Non-ACK (NACK) message to the transmitter. Upon receiving the ACK message from the receiver, the transmitter transmits a new packet. In contrast, upon receiving the NACK message, the transmitter retransmits the packet to the receiver.
To provide a satisfactory radio channel to a terminal traveling in a cell boundary or shadow area, recent wireless communication systems provide a relay service using a relay station. The wireless communication system implementing the relay service can provide a satisfactory radio channel between a base station and the terminal by relaying data transmitted and received between the base station and the terminal by way of the relay station. For doing so, there is a need to implement ARQ using the relay station in the wireless relay communication system.